Patent Document 1 (JP-A-6-333103 Publication) and Patent Document 2 (JP-A-9-231339 Publication) have described an IC card and a memory card which correspond to a dual voltage as external power sources. These have described that a voltage of 3.3V or 5V is supplied from an outside, and the voltage of 5V is dropped to 3.3V by a regulator and the voltage of 3.3V is exactly supplied to an internal circuit.